The present invention relates to a clutch used in transmissions of automobiles to select a power transmission course.
In an automatic transmission for automobiles, a speed change clutch and a start clutch are operated in accordance with a traveling speed of an automobile and output torque of an engine to change speed to a desired speed level. The clutches has a mechanism for pressing input side plates against output side plates to generate a frictional force among the plates to thereby transmit power therebetween. Hereupon, for the purpose of improving the sound stilling property and enhancing strength, a helical gear is used as a gear for transmitting power from a clutch whereby a thrust force is generated due to twist of teeth at the time of transmission of power. Such thrust force has an influence on a pressing force in a clutch to affect power transmitted. Therefore, a system, in which a cushioning member opposing the thrust force is provided, has been devised.
As a conventional example, JP-A-2001-99186 discloses a clutch comprising a helical gear rotatably mounted on a shaft and a clutch mechanism provided on the shaft to make engagement and disengagement of the helical gear from the shaft, wherein a cushioning member opposing a thrust force is provided on a thrust bearing part for rotatably holding the helical gear in a predetermined position on the shaft in an axial direction. According to such a clutch, in the case where the helical gear tends to be moved axially by a thrust force generated when the helical gear transmits power, the cushioning member inhibits movement of the helical gear to prevent vibrations and inclination of the helical gear, thus making an operation of the clutch stable.
According to the above clutch, it is possible to cushion vibrations and inclination of the helical gear, but the clutch will bear a thrust force varying according to power transmitted by the helical gear. While the clutch regulates power transmitted depending upon pressing forces between transmission members, the pressing forces are affected by the varying thrust force whereby transmitting power is in some cases varied. Thus, it is necessary to cause the clutch to operate so as to eliminate such influences.
An object of the invention is to provide a clutch with good controllability, in which influences of a thrust force are eliminated as well as those due to vibrations and inclination of a helical gear.
Under the object, according to the present invention, there is provided a clutch for automobiles, comprising a first transmission member mounted on a shaft to be constrained in a direction of rotation; a second transmission member arranged to be coaxial with the first transmission member, a helical gear, which is arranged to be coaxial with the second transmission member and on which the second transmission member are provided to be constrained in a direction of rotation; an actuator for controlling a state of contact between the first transmission member and the second transmission member; and a stopper restricting positions of the first transmission member and the second transmission member in an axial direction, wherein there is provided a transmission course which is distinguished from the first and second transmission members and through which a thrust force generated on the helical gear or an axial movement of the helical gear is transmitted to the stopper.
Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings.